Generally, when people communicate with each other or interact with a machine via electronic communication device such as a mobile phone, an interphone, and the like, the interactions between the people are often in a noisy background environment. In this situation, sound obtained by the receiver not only includes the voice of the sender but also includes other sounds around the sender, such as voices of other people, sound of steps, collision sound of objects, music, sound of vehicles, and the like. These background sounds except the voice of the receiver and the sender may affect quality of communication. Eliminating the background sound is one of methods for improving the quality of communication.